Is this even a question? Andrew Bird, hands down. Those people will be married for a while, I bet. You can always host a bash in their honor later (if you end up liking them as a married couple, that is).

i bet you could cameo at the bbq, and then head to the concert. here's my deal with soon to be married people: do they even care if anyone else is there? no. they are pretty much interested in each other--which is great. so i never feel bad skipping out on wedding type things like receptions, bbqs, etc. because i know that no one will really know or remember whether or not i came!